The ibuprofen dosage commonly taken by high-level male athletes can afflict their testicles with a condition seen often in elderly men and linked to lower fertility.

That's according to a new study published in the Proceedings of the National Academy of Sciences, which found that heavy usage of the everyday pain medicine "alters human testicular physiology" to result in the disorder called compensated hypogonadism.

The study, which took place in Denmark and France, involved 31 adult men under the age of 35. Some took 1,200 milligrams of ibuprofen daily — the maximum limit as often directed — over a six-week period. Others took a placebo.

Within two weeks, testosterone-producing hormones in the ibuprofen subjects became tied to the amount of ibuprofen in their blood. The ratio of such hormones to testosterone dropped, causing compensated hypogonadism. The disorder is also linked to depression and strokes, the study's authors note.

The authors concluded that "we report a univocal depression of important aspects of testicular function, including testosterone production, after use of over-the-counter ibuprofen."

The study aims at concern over declining reproductive health in men, the authors say. A review last summer in the journal Human Reproduction Update found total sperm count among men in Western continents (including North America) plummeted 59% over a nearly 40-year span ending in 2011.

The disorder remains totally reversible when the ibuprofen is taken over a brief window of time, Bernard Jégou, a co-author at French National Institute of Health and Medical Research, told CNN. That includes the study's subjects, he said.

What remains unknown — and will require more research — is whether effects of taking such ibuprofen dosages over a longer period, as elite athletes often to, can be reversed, Jégou told the network.